-LRB- CNN -RRB- -- Qantas , Australia 's national airline , grounded its Airbus A380 fleet indefinitely after one of its planes suffered a midair engine failure on Thursday .

The airline said flights of the twin-deck planes -- the world 's largest airliners -- will remain suspended until an investigation into Thursday 's incident is complete .

`` As long as it takes , '' said airline CEO Alan Joyce , when a reporter asked how long the suspension would last . `` We are being very cautious until we know exactly what caused this . ''

One of the four engines on a Qantas airliner shut down six minutes after takeoff Thursday from Singapore 's Changi Airport , Joyce said . The plane -- with 440 passengers and 26 crew members -- was headed to Sydney , Australia , but it returned to Changi .

While in the air above the western Indonesian island of Batam , part of the engine 's covering , or cowling , tore off .

`` I am not sure what actually happened with the debris and why parts of the engine left the aircraft and fell into the ground , '' Joyce said . `` We 're still looking at what exactly was the cause of that . ''

The pilot made an announcement updating passengers during the flight .

`` I do apologize , '' the pilot said . `` I 'm sure you are aware we have a technical issue with our number two engine . We have dealt with the situation , the aircraft is secure at this stage . We 're going to have to hold for some time whilst we do lighten our load by dumping some fuel and a number of checklist -LSB- items -RSB- we have to perform .

`` I 'm sure you are aware we are not proceeding to Sydney at this stage . We 're making a left turn now to track back toward Singapore and as we progress with this we 'll keep you informed , but at this stage everything is secure , the aircraft is flying safely and we 'll get back to you very shortly with further information . Thank you for your patience . ''

Local television stations in Indonesia showed debris parts with red-white markings . Pictures of the Airbus A380 after it landed showed the cowling torn off in the back half .

Trifuadi , a security officer at an engineering firm in Batam , said he heard a loud explosion and saw smoke coming out of the engine of a plane flying overhead .

Shortly afterward , debris fell from the plane to the ground , said Trifuadi who , like many Indonesians , goes by one name .

The flight -- QF32 -- landed in Singapore safely , without injury to passenger or crew .

Passenger Meg Graham said she heard a loud bang within minutes of the plane taking off . `` And then another bang , '' she said .

Ulf Waschbusch , who said he was on his way to Australia for the first time , said the crew kept passengers apprised of what was happening .

`` We all stayed pretty calm , '' he told CNN . `` It was an almost eerie calm . ''

The airline said it will work with the plane 's manufacturer as well as Rolls-Royce , the maker of the engine , to determine what went wrong . A spokesman for the Rolls-Royce told CNN that `` safety is always our highest priority . We are currently analyzing the available information and working with our customers to support their operations . ''

Qantas now has six A380s in its fleet of 191 planes . Airbus will at some point deliver another 14 , the airline said .

Singapore Airlines announced Thursday that it has temporarily halted flights of its 11 Airbus A380s to do precautionary checks in light of the Qantas incident .

Lufthansa , which operates three Airbus A380s , told CNN it is planning to carry out additional precautionary checks on the engines of the planes . The airline is waiting for more detail from Rolls-Royce about the specific checks that need to be carried out before they proceed .

CNN 's Christabelle Fombu , Nicky Robertson , Judy Kwon , Kevin Voigt , Liz Neisloss , Ayesha Durgahee and Mia Anngre contributed to this report

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A passenger says she heard a loud bang , then another

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Qantas has six A380s in its fleet of 191 planes

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Singapore Airlines temporarily halts flights of its A380s

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The Airbus A380 is the largest planes in the world